The platform

The platform from a performance perspective (HTML)

Before you start learning performance tips and tricks, it's helpful to understand a bit about how the Windows 8 platform is built and how your app's code is executed.

The app host architecture

When the user launches an app, the system creates an app container and the app host process. The app host loads the Windows Store app using JavaScript and provides it with an execution environment.

The host architecture

This host process has three key components:

  • WinJS
  • The Web Platform
  • The Windows Runtime


The Windows Library for JavaScript (WinJS) is a JavaScript library that gives you UI infrastructure, controls, and other components to make apps that look, feel, and work like full-featured Windows Store apps.

The Web Platform

The Web Platform is a shared component that powers both Internet Explorer and the Windows Store app using JavaScript platform. A Windows Store app using JavaScript can use features that web pages running in the browser use for performance improvements (such as the app cache, temporary internet files, cookies, and IndexedDB). The Web Platform contains multiple subsystems, such as the layout engine, the JavaScript engine, and the Document Object Model (DOM). Apps use these subsystems heavily during execution, and their performance affects your app's performance.

The Windows Runtime

The app host also provides integration with the Windows Runtime. The Windows Runtime integrates your app with Windows and provides many of the APIs for file access, application contracts, device access, and notification services. The Windows Runtime is a separate component from both the DOM and the JavaScript engine.

Related topics

Create your first Windows Store app using JavaScript
The Windows Runtime



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